I applied online. The process took 3 months. I interviewed at Canonical in Feb 2022
Interview
After initial CV sifting, you're invited to a "written interview" in which you submit answers to a set of questions, where the same questions are put to all candidates. If this is successful you go through several rounds of interviews, ultimately 10 hour-long remote interviews over three months. The final stage is a remote interview with Mark Shuttleworth.
Interview questions [1]
Question 1
What did you do in school (education to age 18) or university (first degree to about age 21) that was exceptional? (academically)